Apple macOS up to 11.5.2 WebKit use after free

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.9	$0-$5k	0.00

Summaryinfo

A vulnerability categorized as critical has been discovered in Apple macOS up to 11.5.2. Impacted is an unknown function of the component WebKit. Executing a manipulation can lead to use after free. This vulnerability is registered as CVE-2021-30858. It is possible to launch the attack remotely. Furthermore, an exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Apple macOS up to 11.5.2 (Operating System) and classified as critical. This vulnerability affects an unknown functionality of the component WebKit. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability.

The weakness was published 09/13/2021 as HT212804 as confirmed advisory (Website). The advisory is shared for download at support.apple.com. This vulnerability was named CVE-2021-30858. Successful exploitation requires user interaction by the victim. Technical details are unknown but a private exploit is available. The advisory points out:

Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited.

It is declared as attacked. The vulnerability scanner Nessus provides a plugin with the ID 236674 (Alibaba Cloud Linux 3 : 0079: webkit2gtk3 (ALINUX3-SA-2021:0079)), which helps to determine the existence of the flaw in a target environment. This issue was added on 11/03/2021 to the CISA Known Exploited Vulnerabilities Catalog with a due date of 11/17/2021:

Apply updates per vendor instructions.

Upgrading to version 11.6 eliminates this vulnerability. A possible mitigation has been published immediately after the disclosure of the vulnerability. The advisory contains the following remark:

A use after free issue was addressed with improved memory management.

The vulnerability is also documented in the databases at Zero-Day.cz (662) and Tenable (236674). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Operating System

Vendor

Apple

Name

macOS

Version

License

commercial

Website

Vendor: https://www.apple.com/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.9

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 8.8
NVD Vector: 🔍

CNA Base Score: 8.8
CNA Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
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💳	💳	💳	💳	💳	💳
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Access: Private
Status: Attacked

EPSS Score: 🔍
EPSS Percentile: 🔍

KEV Added: 🔍
KEV Due: 🔍
KEV Remediation: 🔍
KEV Ransomware: 🔍
KEV Notice: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 236674
Nessus Name: Alibaba Cloud Linux 3 : 0079: webkit2gtk3 (ALINUX3-SA-2021:0079)

Zero-Day.cz: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Upgrade: macOS 11.6

Timelineinfo

04/13/2021 🔍
09/13/2021 +153 days 🔍
09/13/2021 +0 days 🔍
09/21/2021 +8 days 🔍
05/18/2025 +1335 days 🔍

Sourcesinfo

Vendor: apple.com

Advisory: HT212804
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2021-30858 (🔍)
GCVE (CVE): GCVE-0-2021-30858
GCVE (VulDB): GCVE-100-183100
scip Labs: https://www.scip.ch/en/?labs.20180712

Entryinfo

Created: 09/21/2021 11:27
Updated: 05/18/2025 16:20
Changes: 09/21/2021 11:27 (18), 09/21/2021 11:30 (30), 09/30/2021 14:34 (3), 09/30/2021 14:35 (18), 04/21/2024 17:56 (23), 05/15/2024 17:15 (1), 06/25/2024 03:46 (2), 07/29/2024 22:36 (1), 09/15/2024 00:30 (1), 01/30/2025 00:15 (11), 05/03/2025 11:14 (3), 05/18/2025 16:20 (2)
Complete: 🔍
Cache ID: 216::103